“There’s a big difference in this race,” Biden said, according to the pool report. “Barack Obama’s not at the head of the ticket. And that means those legions of African Americans and Latinos are not automatically going to come out. No one has energized them like Barack Obama. But he’s not on the ticket. So don’t take this one for granted.”

Leaving aside for a moment the unintentional racism of assuming minority groups vote as a bloc for members of other minority groups, Biden is right on one point: much of the Democrats’ success over the previous six years came in large part due to voters excited about President Obama himself. Yes, the 2012 campaign team made unprecedented use of data to identify supporters, but they did so in the name of an exciting candidate.

Edward Markey doesn’t excite people they way Obama does. Joe Manchin, Max Baucus, and Tim Johnson probably wouldn’t, either, which is a big reason they aren’t running for re-election in 2014. Corey Booker might, but outside of him or a similar candidate rising through the ranks, the Democrats won’t have candidates who can duplicate Obama’s success.

That’s not an indictment of the Democrats yet – politicians like Obama don’t come around all that often, and the Republican ranks only have a few political rock stars of their own. But it will become an indictment if Democrats feel like Obama will carry them to victory again in 2014 and 2016.